JP-A 57-118512, JP-A 57-150609 and JP-A 6-145046 disclose a method of producing a sustained-release microcapsule from a W/O type emulsion using a biodegradable polymer.
A sustained-release biodegradable polymer is useful as, for example, a base material for a physiologically active substance-enclosing microcapsule or the like. It is known that polylactic acid, a copolymer of lactic acid and glycolic acid or the like is useful as such a biodegradable polymer (e.g., JP-A 11-269094).
JP-A 7-97334 discloses a sustained-release preparation comprising a physiologically active substance or a salt thereof and a biodegradable polymer having terminal carboxyl, and a process for producing the sustained-release preparation.
An object of the present invention is to provide a process for producing a sustained-release composition which allows stable formation of a W/O type emulsion, a sustained-release composition produced by said process, and the like.